Separator for fuel battery

ABSTRACT

To provide a separator for a fuel battery in which a gasket is integrally formed with rubber in gasket forming grooves provided in a separator main body without the gasket forming grooves being damaged at a time of forming with the rubber and sealing performance being lowered due to the damage of the separator, the separator for the fuel battery is structured such that a groove width of the gasket forming groove formed in one surface of the separator main body is made larger than a groove width of the gasket forming groove formed in the other surface, or groove side surfaces in the gasket forming groove are formed in an inclined shape, or a curvature is provided in corner portions of a groove bottom surface.

This is a nationalization of PCT application of InternationalPublication No. WO 2005/004264 published on Jan. 13, 2005 and publishedin Japanese.

TECHNICAL FIELD

The present invention relates to a separator for a fuel battery.

BACKGROUND ART

A proton-exchange membrane fuel battery is a battery generating electricpower by using a principle of gaining electricity in the process ofreacting hydrogen with oxygen (an air) so as to obtain water. The fuelbattery is constituted by a fuel battery stack in which a cell is formedby an electrolyte membrane transmitting hydrogen ions and two separatorsbetween which the electrolyte membrane is inserted and a plurality ofthe cells are layered. In this case, a function of shielding thehydrogen and the oxygen, and conductivity capable of gaining theelectricity are required in the separator forming the cell.

Further, since the hydrogen, the oxygen and cooling water are usedwithin the stack, a gasket for sealing them is assembled together.However, since a considerable man-hour is required for assembling thegasket within the stack after the gasket having been independentlyformed, a method of integrally forming the gasket in a separator mainbody has been proposed, and there has been also proposed a method offorming a gasket forming groove on a surface of a separator main bodyfor preventing a gasket lip from being displaced due to an internalpressure and forming a through hole within the gasket forming groove,thereby fixing the gasket to both the surfaces of the separator mainbody on the basis of an anchor effect of the through hole, for example,in the invention described in Japanese Unexamined Patent Publication No.2001-185174.

On the other hand, a material of the gasket conventionally employed issilicone rubber corresponding to liquid rubber having low viscosity,however, there have been generated problems such as transmission ofhydrogen, precipitation of silicone, swelling of silicone rubber and thelike. As a countermeasure thereof, it has been proposed, by theinvention described in Japanese Unexamined Patent Publication No.2002-50369, that EPDM or fluorine-contained rubber corresponding acompound type rubber having high viscosity is used in place of thesilicone rubber.

However, in the case that the gasket is integrally formed in theseparator main body, the silicone rubber can be formed at low injectionpressure and gives no damage to the separator due to the low viscosityin the liquid phase of the silicone rubber. However, in the case ofusing the EPDM or the fluorine-contained rubber is used, high injectionpressure is required due to the high viscosity, so that as shown in FIG.10, there are generated a problem that a bottom surface 10 a or 11 a ofthe gasket forming groove is punched out by the rubber pressure, and aproblem that a groove bottom surface corner portion 14 is punched out bythe rubber pressure in a portion in which a side surface strength of thegasket forming groove is low, whereby a damage portion 15 is generated.Accordingly, there has been a problem that a sealing performance isdeteriorated due to the damage of the separator main body.

Further, when the separator main body is made thinner for making thefuel battery compact in size and light in weight, there has been aproblem that a bottom surface of the forming groove and a corner portionof the groove bottom surface are damaged at a time of forming with theliquid rubber or the like under low injecting pressure. Further, even inthe gasket forming groove having the structure in which the through holeis not provided, when a groove such as a forming groove, an adhesiongroove or the like is formed in the back of the gasket forming groove, astress is concentrated, so that there is a problem that the bottomsurface of the gasket forming groove is damaged.

Patent Document 1: Japanese Unexamined Patent Publication No.2001-185174

Patent Document 2: Japanese Unexamined Patent Publication No.2002-050369

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

The present invention is made by taking the points mentioned above intoconsideration, and an object of the present invention is to provide aseparator for a fuel battery in which a gasket is integrally formed inboth surfaces of a separator main body by arranging a through hole ingasket forming grooves provided in the separator main body and formingis made with rubber, and in which the gasket forming groove portion canbe prohibited from being damaged without a problem that a bottom surfaceof the gasket forming groove is punched out by a pressure of the rubber,and a problem that a corner portion of a groove bottom surface in aportion having a low side surface strength in the gasket forming grooveis punched out by the pressure of the rubber, even in the case of beingformed at a high injection pressure for using high viscosity type EPDMor fluorine-contained rubber for a material of the gasket, whereby it ispossible to prevent a sealing performance from being lowered on thebasis of a damage of the separator.

Further, an object of the present invention is to provide a separatorfor a fuel battery having a gasket forming groove in which a bottomsurface of the forming groove and a corner portion of the groove bottomsurface are not damaged by the pressure of the liquid rubber or the likeeven at a time of forming with the liquid rubber or the like at the lowinjection pressure, in the forming groove having the through hole formedin the separator main body which becomes thinner on the basis of thesize reduction and the weight reduction of the fuel battery.

Further, an object of the present invention is to provide a separatorfor a fuel battery having a gasket forming groove in which a bottomsurface of the forming groove is not damaged by the pressure of therubber or the like at a time of injection molding with the rubber or thelike in the forming groove having no through hole and having the grooveformed on the back in the separator main body in which the grooves areformed in both surfaces.

Means for Solving the Problem

In order to achieve the objects mentioned above, in accordance with afirst aspect of the present invention, there is provided a separator fora fuel battery in which a through hole is provided in gasket forminggrooves provided in a separator main body and forming is made withrubber, whereby a gasket is integrally formed in both surfaces of theseparator main body, wherein a groove width of the gasket forming grooveformed in one surface of the separator main body is made wider than agroove width of the gasket forming groove formed in the other surface.

Further, in accordance with a second aspect of the present invention,there is provided a separator for a fuel battery in which a through holeis provided in gasket forming grooves provided in a separator main bodyand forming is made with rubber, whereby a gasket is integrally formedin both surfaces of the separator main body, wherein groove sidesurfaces in the gasket forming grooves formed in the separator main bodyare formed in an inclined shape.

Further, in accordance with a third aspect of the present invention,there is provided a separator for a fuel battery in which a through holeis provided in a gasket forming groove provided in a separator main bodyand forming is made with rubber, whereby a gasket is integrally formedin both surfaces of the separator main body, wherein a curvature isprovided in corner portions of groove bottom surfaces in the gasketforming grooves formed in the separator main body.

Further, in accordance with a fourth aspect of the present invention,there is provided a separator for a fuel battery in which forming ismade with rubber in a gasket forming groove formed in at least one ofsurfaces of a separator main body having grooves formed in bothsurfaces, whereby a gasket is formed in the separator main body, whereina groove width of the gasket forming groove formed in one surface of theseparator main body is made wider than a groove width of the grooveformed in the other surface being the back of the gasket forming groove.

Further, in accordance with a fifth aspect of the present invention,there is provided a separator for a fuel battery in which forming ismade with rubber in a gasket forming groove formed in at least one ofsurfaces of a separator main body having grooves formed in bothsurfaces, whereby a gasket is formed in the separator main body, whereingroove side surfaces in the gasket forming groove formed in one surfaceof the separator main body and in the groove formed in the other surfacebeing the back of the gasket forming groove are formed in an inclinedshape.

Further, in accordance with a sixth aspect of the present invention,there is provided a separator for a fuel battery in which forming ismade with rubber in a gasket forming groove formed in at least one ofsurfaces of a separator main body having grooves formed in bothsurfaces, whereby a gasket is formed in the separator main body, whereina curvature is provided in corner portions of groove bottom surfaces inthe gasket forming groove formed in one surface of the separator mainbody and in the groove formed in the other surface being the back of thegasket forming groove.

In accordance with the separator for the fuel battery on the basis ofthe first to third aspects of the present invention provided with thestructure mentioned above, since the groove width of the gasket forminggroove formed in one surface is made larger than the groove width of thegasket forming groove formed on the other surface, or the groove sidesurface of the gasket forming groove is formed in the inclined shape, orthe curvature is provided in the corner portion of the groove bottomsurface, it is possible to prevent the problem that the bottom surfaceof the gasket forming groove is punched out by the pressure of therubber even in the case of being formed under the high injectionpressure by using the high viscosity compound type EPDM,fluorine-contained rubber or the like. Further, it is possible toprevent the problem that the corner portion of the groove bottom surfacein the portion having the low side surface strength in the gasketforming groove is punched out by the pressure of the rubber.

Further, in accordance with the separator for the fuel battery on thebasis of the first to third aspects of the present invention providedwith the structure mentioned above, it is possible to prevent theproblem that the bottom surface of the gasket forming groove is punchedout by the pressure of the rubber even in the case that the separatormain body is made thinner on the basis of the reduction in size and thereduction in weight of the fuel battery and injection molding is madewith the liquid rubber under the low output. Further, it is possible toprevent the problem that the corner portion of the groove bottom surfacein the portion having the low side surface strength in the gasketforming groove is punched out by the pressure of the rubber.

Further, in accordance with the separator for the fuel battery on thebasis of the fourth to sixth aspects of the present invention providedwith the structure mentioned above, since the groove width of the gasketforming groove formed in one surface of the separator main body is madelarger than the groove width of the groove formed in the other surfacebeing the back of the forming groove, or the groove side surface of thegasket forming groove and the groove formed in the back surface of thegasket forming groove is formed in the inclined shape, or the curvatureis provided in the corner portion of the groove bottom surface, it ispossible to prevent the problem that the bottom surface of the gasketforming groove is punched out by the pressure of the rubber even in thecase that injection molding is made with the rubber or the like in thegasket forming groove from being generated.

EFFECT OF THE INVENTION

In the separator for the fuel battery in accordance with the first tothird aspects of the present invention provided with the structurementioned above, since it is possible to prevent the problem that thebottom surface of the gasket forming groove is punched out by thepressure of the rubber even in the case of being formed under the highinjection pressure by using the high viscosity compound type EPDM,fluorine-contained rubber or the like and the problem that the cornerportion of the groove bottom surface in the portion having the low sidesurface strength in the gasket forming groove is punched out by thepressure of the rubber, it is possible to inhibit the gasket forminggroove from being damaged, whereby it is possible to prevent the sealingperformance from being lowered due to the damage of the separator.

Further, in the separator for the fuel battery in accordance with thefirst to third aspects of the present invention provided with thestructure mentioned above, since it is possible to prevent the problemthat the bottom surface of the gasket forming groove is punched out bythe pressure of the rubber even in the case that the separator main bodyis made thinner on the basis of the reduction in size and the reductionin weight of the fuel battery and injection molding is made with theliquid rubber under the low output, and the problem that the cornerportion of the groove bottom surface in the portion having the low sidesurface strength in the gasket forming groove is punched out by thepressure of the rubber, it is possible to inhibit the gasket forminggroove from being damaged, whereby it is possible to prevent the sealingperformance from being lowered due to the damage of the separator.

Further, in the separator for the fuel battery in accordance with thefourth to sixth aspects of the present invention provided with thestructure mentioned above, since it is possible to prevent the problemthat the bottom surface of the gasket forming groove is punched out bythe pressure of the rubber even in the case that injection molding ismade with the rubber or the like in the gasket forming groove from beinggenerated, it is possible to inhibit the gasket forming groove frombeing damaged, whereby it is possible to prevent the sealing performancefrom being lowered due to the damage of the separator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a separator for a fuel battery inaccordance with an embodiment of the present invention;

FIG. 2 is a partial plan view of a separator main body structuring theseparator for the fuel battery in accordance with the embodiment of thepresent invention;

FIG. 3 is a cross sectional view of a main portion of a separator for afuel battery in accordance with a first embodiment of the presentinvention;

FIG. 4 is a cross sectional view of a main portion of a separator for afuel battery in accordance with a second embodiment of the presentinvention;

FIG. 5 is a cross sectional view of a main portion of a separator for afuel battery in accordance with a third embodiment of the presentinvention;

FIG. 6 is a cross sectional view of a main portion of a separator for afuel battery in accordance with a fourth embodiment of the presentinvention;

FIG. 7 is a cross sectional view of a main portion of a separator for afuel battery in accordance with a fifth embodiment of the presentinvention;

FIG. 8 is a cross sectional view of a main portion of a separator for afuel battery in accordance with a sixth-embodiment of the presentinvention;

FIG. 9 is a cross sectional view of a main portion of a separator for afuel battery in accordance with a seventh embodiment of the presentinvention;

FIG. 10 is a cross sectional view of a main portion of a separator for afuel battery in accordance with an eighth embodiment of the presentinvention;

FIG. 11 is a cross sectional view of a main portion of a separator for afuel battery in accordance with a ninth embodiment of the presentinvention; and

FIG. 12 is a cross sectional view of a main portion of a separator for afuel battery in accordance with a conventional example.

DESCRIPTION OF REFERENCE NUMERAL

-   -   1 separator for fuel battery    -   2 separator main body    -   2 a, 2 b surface of separator main body    -   3 gasket    -   4 through hole    -   5, 7 pedestal portion    -   6, 8 lip portion    -   9 connection portion    -   10, 11 forming groove    -   10 a, 11 a groove bottom surface portion    -   12, 13 buried portion    -   14 corner portion of groove bottom surface    -   15 damaged portion    -   16, 17 groove side surface

BEST MODE FOR CARRYING OUT THE INVENTION

A description will be given below of preferable embodiments inaccordance with the invention with reference to the accompanyingdrawings. In this case, the scope of the invention is not limited to thecontents described in the embodiments unless being particularlydescribed.

First Embodiment

FIG. 1 is a schematic view of a separator 1 for a fuel battery inaccordance with a first embodiment of the present invention, FIG. 2 is apartial plan view of a separator main body 2 structuring the separator 1for the fuel battery, and FIG. 3 is a cross sectional view of a mainportion along a line A-A in FIG. 1.

The fuel battery separator 1 in accordance with the first embodimentmentioned above has the separator main body 2 and a gasket 3respectively as constituting parts, as shown in FIG. 1, and theconstituting parts are structured as follows.

First, gasket forming grooves 10 and 11 are respectively formed in bothsurfaces 2 a and 2 b of the separator main body 2, in which a mixture ofa carbon powder and a phenol corresponding to a thermosetting resin iscompression molded, along an extending direction of a gasket as shown inFIG. 2, and a desired number of through holes 4 are formed along boththe forming grooves 10 and 11 in such a manner as to communicate betweenbottom surfaces 10 a and 11 a of both the forming grooves 10 and 11. Inthis case, as shown in FIG. 3, in a groove width of the forming grooves10 and 11 formed in both the surfaces 2 a and 2 b of the separator mainbody 2, a groove width D of one surface 2 a is set larger than a groovewidth d of the other surface 2 b. In particular, a rate (D/d) of thegroove width of the forming groove is preferably 105% or more, and morepreferably between 120 and 200%.

The gasket 3 is integrally provided with a buried portion 12 arrangedwithin the forming groove 10 in one surface 2 a side of the separatormain body 2, a pedestal portion 5 supported to the buried portion 12 soas to protrude out of the forming groove 10, a lip seal portion 6supported to the pedestal portion 5 and having a chevron cross sectionalshape, a buried portion 13 arranged within the forming groove 11 in theother surface 2 b side of the separator main body 2, a pedestal portion7 supported to the buried portion 13 so as to protrude out of theforming groove 11, a lip seal portion 8 supported to the pedestalportion 7 and having a chevron cross sectional shape, and a connectionportion 9 arranged in the through hole 4 and connecting both the buriedportions 12 and 13.

Second Embodiment

FIG. 4 is a cross sectional view of a main portion of a separator 1 fora fuel battery in accordance with a second embodiment of the presentinvention. The fuel battery separator 1 in accordance with the secondembodiment mentioned above has a separator main body 2 and a gasket 3respectively as constituting parts, and the constituting parts arestructured as follows.

First, gasket forming grooves 10 and 11 are respectively formed in bothsurfaces 2 a and 2 b of the separator main body 2, in which a mixture ofa carbon powder and a phenol corresponding to a thermosetting resin iscompression molded, along an extending direction of a gasket as shown inFIG. 2, and a desired number of through holes 4 are formed along boththe forming grooves 10 and 11 in such a manner as to communicate betweenbottom surfaces of both the gasket forming grooves 10 and 11. In thiscase, as shown in FIG. 4, groove side surfaces 16 and 17 in the gasketforming grooves 10 and 11 formed in both the surfaces 2 a and 2 b of theseparator main body 2 are formed in an inclined shape.

The gasket 3 is integrally provided with a buried portion 12 arrangedwithin the forming groove 10 in one surface 2 a side of the separatormain body 2, a pedestal portion 5 supported to the buried portion 12 soas to protrude out of the forming groove 10, a lip seal portion 6supported to the pedestal portion 5 and having a chevron cross sectionalshape, a buried portion 13 arranged within the forming groove 11 in theother surface 2 b side of the separator main body 2, a pedestal portion7 supported to the buried portion 13 so as to protrude out of theforming groove 11, a lip seal portion 8 supported to the pedestalportion 7 and having a chevron cross sectional shape, and a connectionportion 9 arranged in the through hole 4 and connecting both the buriedportions 12 and 13.

Third Embodiment

FIG. 5 is a cross sectional view of a main portion of a separator 1 fora fuel battery in accordance with a third embodiment of the presentinvention. The fuel battery separator 1 in accordance with the thirdembodiment mentioned above has a separator main body 2 and a gasket 3respectively as constituting parts, and the constituting parts arestructured as follows.

First, gasket forming grooves 10 and 11 are respectively formed in bothsurfaces 2 a and 2 b of the separator main body 2, in which a mixture ofa carbon powder and a phenol corresponding to a thermosetting resin iscompression molded along an extending direction of a gasket as shown inFIG. 2, and a desired number of through holes 4 are formed along boththe forming grooves 10 and 11 in such a manner as to communicate betweenbottom surfaces of both the forming grooves 10 and 11. In this case, asshown in FIG. 5, a curvature is provided in a groove bottom surfacecorner portion 14 in the gasket forming grooves 10 and 11 formed in boththe surfaces 2 a and 2 b of the separator main body 2.

The gasket 3 is integrally provided with a buried portion 12 arrangedwithin the forming groove in one surface 2 a side of the separator mainbody 2, a pedestal portion 5 supported to the buried portion 12 so as toprotrude out of the forming groove 10, a lip seal portion 6 supported tothe pedestal portion 5 and having a chevron cross sectional shape, aburied portion 13 arranged within the forming groove 11 in the othersurface 2 b side of the separator main body 2, a pedestal portion 7supported to the buried portion 13 so as to protrude out of the forminggroove 11, a lip seal portion 8 supported to the pedestal portion 7 andhaving a chevron cross sectional shape, and a connection portion 9arranged in the through hole 4 and connecting both the buried portions12 and 13.

Fourth Embodiment

In the first embodiment to the third embodiment mentioned above, thereare exemplified the case that a position of the through hole and aposition of the lip region contributing to a sealing performance of thegasket are overlapped. However, a fourth embodiment shows the case thata position of the through hole 4 and a position of a lip region Econtributing to the sealing performance are arranged at offsetpositions. In this case, the “lip region E contributing to the sealingperformance of the gasket” corresponds to a range between one third andone half of a height h of the seal lip 3. If a shrinkage is formed in abottom side therefrom, the sealing performance is affected at a verysmall level. Accordingly, the lip region E is slightly smaller than anentire width of the lip 3.

Fifth Embodiment

Further, it is not necessary that the shape of the gasket forming groove10 formed in one surface 2 a is the same as the shape of the gasketforming groove 11 formed in the other surface 2 b, and as in a fifthembodiment shown in FIG. 7, only a groove side surface 17 of the gasketforming groove 11 formed in the other surface 2 b may be formed in aninclined shape.

Sixth Embodiment

Further, it is not necessary that the shape of the gasket forming groove10 formed in one surface 2 a is the same as the shape of the gasketforming groove 11 formed in the other surface 2 b in the same manner asthe fifth embodiment, and as in a sixth embodiment shown in FIG. 8,there can be employed a case that the gasket forming groove 10 formed inone surface 2 a is formed in a shape in which the curvature is providedin the groove bottom surface corner portion 14, and the gasket forminggroove 11 formed in the other surface 2 b has a groove side surface 17in an inclined shape.

Seventh Embodiment

FIG. 9 is a cross sectional view of a main portion of a separator 1 fora fuel battery in accordance with a seventh embodiment of the presentinvention, and shows a case that the through hole communicating theforming groove 10 formed in one surface 2 a with the forming groove 11formed in the other surface 2 b is not formed.

In this case, a groove width D of the gasket forming groove 10 formed inone surface 2 a is set larger than a groove width d of the forminggroove 11 formed in the other surface 2 b being the back of the forminggroove 10. In particular, a rate (D/d) of the groove width of theforming grooves 10 and 11 is preferably 105% or more, and morepreferably between 120 and 200%. In this case, the groove 11 formed inthe other surface 2 b is described as the forming groove, however, itmay be employed to an adhesion groove or the like in place of theforming groove.

Embodiment 8

FIG. 10 is a cross sectional view of a main portion of a separator 1 fora fuel battery in accordance with an eighth embodiment of the presentinvention, and shows a case that the through hole is not formed in thesame manner as the seventh embodiment, and shapes of groove sidesurfaces 16 and 17 in a gasket forming groove 10 formed in one surface 2a and in a forming groove 11 formed in the other surface 2 b being theback of the gasket forming groove 10 are formed in an inclined shape. Inthis case, the groove 11 formed in the other surface 2 b is described asthe forming groove in the present embodiment, however, it may beemployed to an adhesion groove or the like in place of the forminggroove.

Ninth Embodiment

FIG. 11 is a cross sectional view of a main portion of a separator 1 fora fuel battery in accordance with a ninth embodiment of the presentinvention, and shows a case that the through hole is not formed in thesame manner as the seventh embodiment and the eighth embodiment. Acurvature is provided in a groove bottom surface corner portion 14 in agasket forming groove 10 formed in one surface 2 a and in a forminggroove 11 formed in the other surface 2 b being the back of the gasketforming groove 10. In this case, the groove 11 formed in the othersurface 2 b is described as the forming groove in the presentembodiment, however, it may be employed to an adhesion groove or thelike in place of the forming groove.

In this case, the material used in the separator main body 2 inaccordance with the first embodiment to the ninth embodiment may be amixture of the carbon powder and a thermoplastic resin in addition tothe mixture of the carbon powder and the thermosetting resin.

Further, as the integrally molding method by using the EPDM or thefluorine-contained rubber in the material of the gasket 3 in accordancewith the first embodiment to the ninth embodiment, a transfer moldingmethod may be employed in addition to the injection molding method.

1. A separator for a fuel battery comprising: a separator main body of amixture of a carbon powder and a thermosetting resin, a gasket made of arubber material selected from an EPDM and a fluorine compound rubber andprovided with lip portions on upper and lower surfaces; said separatormain body being provided with two opposed surfaces with each of said twoopposed surfaces including gasket forming grooves, the gasket forminggrooves of said two opposed surfaces being different in shape; and saidgasket forming grooves being provided with a through hole; said gasketbeing integrally formed in both surfaces of said separator main body byattaching said rubber material to said gasket forming grooves; at leastone of groove side surfaces in said gasket forming grooves formed insaid separator main body being inclined downwardly to central parts ofsaid grooves to form an inclined shape.
 2. A separator for a fuelbattery comprising: a separator main body of a mixture of a carbonpowder and a thermosetting resin, a gasket made of a rubber materialselected from an EPDM and a fluorine compound rubber and provided withlip portions on upper and lower surfaces; said separator main body beingprovided with two opposed surfaces with each of said two opposedsurfaces including gasket forming grooves, the gasket forming grooves ofsaid two opposed surfaces being different in shape; and said gasketforming grooves being provided with a through hole; said gasket beingintegrally formed in both surfaces of said separator main body byattaching said rubber material to said gasket forming grooves; and acurvature being provided in corner portions of at least one of groovebottom surfaces in said gasket forming grooves formed in said separatormain body.